A man in his 40s has died after two airport vehicles crashed on the airfield at London's Heathrow Airport.
The collision involved two members of staff.
The Metropolitan Police said a man in his 40s had been taken to a west London hospital in a serious condition and was later pronounced dead.
Police said another man was treated for "non-life-threatening or life-changing injuries", and is understood to have sustained a broken shoulder.
British Airways has confirmed that the man who died was a BA engineer.
Flights were disrupted after the incident and several aircraft preparing to take off were held on the ground following the collision near Terminal 5 shortly after 6am.
At least 20 British Airways flights failed to meet their scheduled departure time after the crash.
It has been reported that some passengers were ordered to leave planes.
A Heathrow spokeswoman said: "We are dealing with a serious accident involving two vehicles on the airfield.
"We are working closely with the emergency services and updates will follow.
"The airfield remains open and we will work to minimise disruption to our passengers' journeys.
"We apologise for any inconvenience caused."
The Health and Safety Executive was informed and officers from the Met's serious collision investigation unit were at the scene.
No arrests were made.
A British Airways spokeswoman said: "We have apologised to customers for the delay to a small number of our flights this morning, following an incident involving two operational vehicles at the airport.
"We are doing all we can to ensure they will be able to depart as soon as possible."